1. Field of the Invention
The present invention relates to underground storage tanks, and particularly to turbulence arresters on drop tubes used to fill underground storage tanks.
2. Background of the Invention
In the United States alone there are approximately five million underground storage tanks used to fuel autos, trucks, planes, etc. Sediment and debris from fuel deliveries or from the tank itself (due to rust, scaling, etc.) accumulate at the bottom of these tanks. Undisturbed, these contaminants would lie on the bottom of the tank and cause no problems. Unfortunately fuel delivery to the tank, which is typically by way of a drop tube installed in the tank, disturbs these contaminants. Therefore fuel filters must be used when dispensing the fuel from the tank. Over time these filters will accumulate deposits of the contaminants and will clog. No fuel can be dispensed from the tank until the filter is changed, an expensive process which disrupts operations for extended periods of time.
Certain fuels, such as diesel, have a tendency to foam during fuel drops. This foam must dissipate before fuel levels in the tank may be accurately read to verify the amount of fuel dropped. Tank owners generally must pay for time spent by delivery persons waiting for the foam to dissipate.
Many underground storage tanks are equipped with continuous in-tank monitors which sound an alarm when water is detected. When water accumulations at the bottom of the tank are disturbed during fuel drops, the alarm may sound unnecessarily.
Known turbulence arresters utilize various arrangements of baffles to slow the fuel's flow velocity as it exits the drop tube. The fuel dispersed into the tank thus produces less turbulence in the fuel already present in the tank and is therefore less likely to disturb contaminants. Such arrangements also impede the delivery of fuel to the tank, thus requiring longer to complete the fuel drop.